Healthy eating. Regular exercise. Both are essential to shedding pounds and changing your life. But it’s tough to break bad habits. The key? Starting from the inside out. Personal fitness guru Bob Harper shows you how…

Millions know Bob Harper as the nice-guy trainer on the NBC hit “The Biggest Loser.” But he’s not afraid to get tough about transforming people’s lives. The Nashville, Tenn., native shaped up Gwyneth Paltrow, Ben Stiller, Ellen DeGeneres and other A-listers for years.

Harper became a star himself after joining “The Biggest Loser” (the reality show that has obese contestants vying to win $250,000 for losing the most weight), which debuted to huge ratings in October 2004.

What’s the 44-year-old fitness guru’s secret to success? No excuses. He commands people to take charge of their bodies through regular exercise, healthy eating and an “inside-out” philosophy.

“It’s about finding that inner strength,” he says, “and wanting to have the best life possible.”

In this Lifescript exclusive, Harper tells us how to beat our bad habits – and keep that weight off for good.

What’s the most common excuse for avoiding regular exercise and healthy eating?Time constraints – juggling work, family and kids.

How do you respond to someone who claims, “I’m too heavy to work out”?I roll my eyes and say, “Hello! Have you ever watched my show? I’ve [had] a guy who’s 525 pounds and [he got] up every single day and [made] it happen, so there’s no excuse… no excuse.”

I have no qualms about saying that to them. I think people become complacent and comfortable. I’m like, “No, it’s time to get uncomfortable.”

How do you get people motivated?They must have that inner resolve; I can’t give it to them. I’ve got to show them, yes, it can be done, and you can do anything you put your mind to. Just take that first step.

Why do so many people find it so hard to stick to regular exercise routines? They get bored. It becomes difficult and monotonous.

I get it! I’ve been in the fitness business for a long time, and I see people get so gung-ho in the beginning. Then all of a sudden it becomes work: “Ugh, I’ve got to get up and get a workout in.”

I encourage them to remember how good they feel after they’ve exercised and eaten properly.

When you fall off the wagon, for lack of a better phrase, you can always pick yourself up and start again. I try to show people this is a lifestyle change, not a quick fix.

How do you inspire the “The Biggest Loser” contestants to break bad habits? It’s different than motivating the average person. When they come on the show, they’re so excited and ready to do practically anything. My job is to give them the tools to live a healthy life, for life.

What kind of tools?I tell them there’s so much information out there when it comes to health and fitness. Reading articles, social networks on the Internet that help support people [such as “The Biggest Loser” Facebook Page and the Lifescript Weightloss Facebook page], having friends and co-workers to start a walking group with – anything so you don’t feel like you’re doing this all alone.

People need the support of friends and family to keep going.

What else should an obese person do when starting a diet and regular exercise program?That’s my specialty, working with obese Americans and showing them the strength they really have. Carrying all that body weight around, they tend to be a lot stronger than people give them credit for.

As soon as you get them on a proper eating schedule and get their cardio going, they’re going to see results. The body wants to be healthy; it doesn’t want to have all this fat on it. It will respond quite quickly.

Is counting calories important?We do this with our contestants, first thing. They have to measure their food to see a proper portion size. Then they can eyeball it. When they’re eyeballing food in the beginning, it’s distorted because they’ve been eating such large portions.

You need to be able to count your calories [so] you know how many are going in and then how many are going out.

What healthy eating tips can you share with us?I like to focus on organic, all-natural food – a lot of plant-based food. I’m a big believer in getting your fruits, vegetables and whole grains in.

What about someone who can’t master cooking? How can they get the benefits of healthy eating, too?I didn’t know how to cook, and I’ve had plenty of people on the show who couldn’t either.

It doesn’t take a college degree to figure it out – it can be done. Actually, The Biggest Loser Cookbook (Rodale Books) is really easy. It’s everything we’ve done on the show.

You recently became a vegetarian. Why?It has been a couple of years now. I feel I’m in the best shape of my life. My epiphany was reading [the tough-love diet book] Skinny Bitch that a girlfriend of mine was reading. It made me think differently about food.

Then I read The China Study, [which examines the link between illnesses and eating animal products]. That book changed my life. That’s when I needed to see what this vegetarian lifestyle was all about.

How does your training style differ from your TV partner, Jillian Michaels?She’ll tell you in a second that I’m the harder trainer. Everyone thinks I’m the nice one. I get into a gym, and I feel it’s like my office and it’s all business there. People don’t know what their capabilities are. It’s my job to show them what they can do.

It’s like being able to own their bodies again. When you have that inner strength to do anything you want, nothing is going to stop you, even if you aren’t able to do the activities I want you to do in the beginning… it will come. It’s the triumph of the spirit.

What fitness obstacles do women face that men don’t?Men have more testosterone, so they can burn fat a lot faster than women. Women have to be more disciplined.

For the longest time, women thought they’d never be able to win our show. We proved that to be very wrong [in season 5, Ali Vincent became the show’s first female winner; 3 women have won in the show’s 9 seasons]. I’ve always said women are stronger than men.

Is it hard to motivate women to commit to regular exercise?Women get afraid of any weight training because they think they’re going to get bigger.

On the contrary, you begin to get a little more lean muscle, and then you’re going to be able to burn the fat. I love doing weight training with women. All of a sudden they do it and see and feel the benefits.

What do women usually want to work on?Their bellies and butts.

With the belly, I always say “cardio.” If you can get that heart rate up 3-5 times a week for at least 30 minutes, you’re going to be burning the fat areas you want.

Anything to get your heart rate up. I’ve had people say, “Oh, Bob, I need to work out, but I hate running.” Well, OK, so don’t run.

I like spinning a lot. I get my people on the show to do spinning classes.

How do we tighten our behinds?Lunges and squats – any kind of weighted activity for the lower body – are really going to hit your glutes and thighs.

When it comes to lunges, I like at least 3 sets of 20 lunges on each leg with one 10-pound weight in your hands. For squats – I call them sumo squats – hold a 20- to 25-pound weight between your legs with your legs out wide. Do 3 sets of 25.

What does fitness mean to you?Overall quality of life.

How old do you want to live to be?I always joke to my friends that the way I eat, I’ll outlive everyone. As long as I’m in complete control of my body and my mind, I’m OK with that.

Are You Ready to Lose Weight?Losing weight is a commitment to diet, exercise and behavioral changes. You know you could stand to lose some of those unwanted pounds, but are you ready to make this life-long commitment, start a diet or start a regular exercise routine? Take this weight-loss quiz to find out.

Check out Health Bistro for more healthy food for thought. See what Lifescript editors are talking about and get the skinny on latest news. Share it with your friends (it’s free to sign up!), and bookmark it so you don’t miss a single juicy post!